Polychlorinated biphenyls (PCBs) and DDT/DDE (DDE is the stored metabolite of DDT) are toxic, widespread pollutants. Both pass from mother to child through the placenta and by contaminating breast milk. This project includes a study of children exposed to low levels of both compounds in North Carolina and a study of persons poisoned by heat- degraded PCBs in Taiwan. In North Carolina, we measured DDE and PCBs in breast milk in about 700 women who had children between 1978 and 1982 and followed the children since. PCBs and DDE can cause long term induction of steroid metabolizing enzymes following exposure early in life. This could change the way the children metabolize sex hormones as they approach puberty. We are collecting data on onset of puberty in these children to see whether their rate of sexual maturation is affected by their perinatal exposures to these compounds. In Taiwan, an epidemic of 2000 cases of PCB poisoning occurred in 1979. We have followed-up the cohort, and found an excess (relative risk of 2.4) of mortality from non- malignant liver disease. Our colleagues in Taiwan have begun interviewing the living members of the cohort, and have preliminary data showing higher rates of goiter in both sexes and anemia in women who were poisoned.